• It saps our time: Every time you get interrupted — like when your phone buzzes with a new email or your Gmail tab compels you toward the inbox — you lose 20 minutes. According to a University of California-Irvine study, that's how long it takes to reacquaint yourself with the details of what you left.

• It slows us down:20 years of psych research shows that switching between tasks takes up to 40% longer than just taking one task at a time.

• It erodes our ability to concentrate: People who multitask all the time have trained their brains out of being able to focus. As Stanford researchers have found, multitasking — like constantly switching between your work and your email — slowly changes your brain structure so that you can't focus.

The best option might be to take strategy consultant Ron Friedman's advice: Change your environment by way of quitting Outlook, closing email tabs, and turning off your phone for a 30-minute chunk of deep-diving work.

"The alternative, which most of us consider the norm, is the cognitive equivalent of dieting in a pastry shop," he writes. "We can all muster the willpower to resist the temptations, but doing so comes with considerable costs to our limited supply of willpower."